The following relates generally to wireless communication, and more specifically to low latency multiplexing operations.
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include fourth generation (4G) systems such as a Long Term Evolution (LTE) systems or LTE-Advanced (LTE-A) systems, and fifth generation (5G) systems which may be referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform-spread-orthogonal frequency division multiplexing (DFT-S-OFDM).
A wireless multiple-access communications system may include a number of base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE). In some wireless communications systems (e.g., NR systems), a base station may communicate with a UE on a carrier using shortened transmission time intervals (sTTIs). For example, the base station may allocate transmission resources of an sTTI to carry a shortened physical downlink shared channel (sPDSCH). In some cases, the allocated resources may collide with one or more broadcast transmissions from the base station. Examples of such broadcast transmissions include primary synchronization signal (PSS), secondary synchronization signal (SSS), and physical broadcast channel (PBCH). Each of these transmissions may occur periodically and be associated with a set of frequency resources (e.g., 72 subcarriers or six resource blocks (RBs)) that are centrally located within a system bandwidth. By way of example, PBCH may occupy the first four symbols of a second slot within each radio frame; PSS may be located over the last symbol of the first slot of the first and sixth subframes within each radio frame; and SSS may be transmitted with the same periodicity as PSS, occupying the symbol preceding the PSS in the first and sixth subframes. When transmission resources allocated for sPDSCH overlap at least partially with symbols allocated for broadcast transmissions, collisions may occur. Such collisions may decrease throughput or otherwise negatively impact the wireless system. The base station may also transmit reference signals to the UE during the sTTI, and the UE may use the reference signals to perform channel estimation to correctly demodulate the data in the sTTI. Efficient techniques for transmitting reference signals within an sTTI may be desirable to reduce overhead in a wireless communications system.